[Plugin: WP Super Cache] Benefits/drawbacks to running WP-SuperCache and Google's mod_pagespeed

Has anyone tried using Google’s new mod_pagespeed Apache plugin with WP-SuperCache? While they operate at two completely different levels of the web transaction (the former at the Apache module level and the latter at the PHP level), they seem to have an overlapping set of functionality. Is anyone using them together? To they co-exist nicely? Is it advantageous to run them together?